This invention refers to apparatus and methods for releasably securing a freight container of standard type (I.S.O. standard) to a loading platform and/or to another container within a stack of a multiplicity of such freight containers.
As is well known in the art, standard freight containers of the type described have at each corner a corner fitting in which there is an elongate orifice in the horizontal face, the orifice opening into a recess within the corner fitting.
The state of the prior art is summarized in U.S. Pat. No. 3,691,595 which teaches and claims a device for vertical lashing comprising a spring operated twist-lock which penetrates the elongate orifice. The device is activated automatically by a vertical compression caused by the weight of a container as the container gravitates into contact with an active member of the device so as to release a force to rotate the twist-lock to a locking position within the recess.
The device of U.S. Pat. No. 3,691,595, while substantially eliminating the drawbacks of the prior art, relies upon active elements for releasable lashing, which active elements require manual activation with a special tool to unlock the twist-lock. When the device is located in an interior position in a stacked block of containers, the procedure for unlocking is time consuming and hazardous, inasmuch as stevedores must climb up and down the container stack in order to activate each release mechanism. Thus the need still exists for a vertical fastener which does not require special tools or human interaction for its release and which will releasably lash containers together irrespective of the height and lateral interrelation between stacks within the same block.
Moreover, what is required is a simple device, preferably without active elements which can cause jamming through failure resulting from corrosion or misuse. The ideal device should be both rugged and inexpensive to manufacture.